California, USA — Chuck O’Brien operates three markets in California’s central valley, where his customers know him for providing fresh food and superior service. He had been looking forward to getting on the renewable energy bandwagon for some time, and early in 2010, he was able to install solar plants at two of his three markets: his Riverbank store installed a 186kW plant and he installed 280kW of generating capacity at one of his Modesto markets.
According to Chuck, there were three things that happened to enable his dream to become a reality: 1) solar panels have come down a lot in price since the early days, 2) O’Brien’s local power company, the Modesto Irrigation District, was offering rebates for companies that put in solar-generating capacity, and 3) O’Brien was able to get the Federal Government to give his business an investment tax credit for not just 30% of the solar hardware, but he was also able to obtain federal funding for the replacement of the roofs on his stores, because the new Solyndra solar panels that were being installed must be mounted on a roof surface that has been specially prepared for them.
In selecting components for the installations, Chuck was adamant that as much of the system as possible be from American suppliers. This is one of the reasons for selecting the panels from Solyndra, a San Francisco Bay Area company. Advanced Energy’s PV Powered commercial inverters were chosen and are manufactured in Bend, Oregon.
Chuck O’Brien selected Panelized Structures Inc. of Modesto, CA as the system vendor and installer with Pacific Solar Energy, Inc. of Pleasanton, CA to do the electrical work, including installing the combiners, inverters, AC interconnection, and hookups to his electrical system.
The cylindrical Solyndra modules that compose the panels are of a unique design compared to traditional flat panel solar arrays. Because of their shape, they collect less dirt than flat arrays and they mount on standoffs above the roof (Fig. 1), freeing installers from requiring absolutely flat roof surfaces for panel installation, and eliminating seismic issues as part of the install process.
Compared to other types of solar arrays, they can be packed more densely and get much of their energy as reflected light from the building roof, which is typically painted white or covered with white material during the install process. The inverters (two 75kW commercial units were installed at the Riverbank, CA market and one 260kW unit was installed at the Modesto store, see Fig. 2) are designed for commercial rooftop projects. To support these installations, each inverter comes with integrated data monitoring equipment and AC/DC disconnects. The wide operating voltage range of the inverters is directly compatible with Solyndra’s panel technology.
|Figure 1. The Solyndra solar modules mount above O’Brien’s Market’s white roof on standoffs.|
Keeping an Eye on Power Production
Chuck O’Brien is able to monitor the power production of his system with the inverter’s data monitoring system. A web-based display illustrates the power output of the system over selectable time periods, enabling Chuck to see performance trends and ensure his investment is producing the power he expected. The monitoring display also provides estimates of the equivalent amount of energy produced in terms of CO2 saved or trees saved by each inverter.
The systems produce close to all the power that the markets need in the daytime, and at some times, the systems are able to actually export power over the grid. O’Brien is expecting to achieve a 5 ½-year payback period on the systems. “We purchased 20 year warranties on the inverters,” said Chuck O’Brien. “So when the payback period is over, we’re expecting to have free power for a long time. We’ve been operating the first system since February (of 2010) and so far, it has been completely trouble free. Think of all the vacant rooftops out there that are not producing energy — venture capital firms should be investing in this. The time is right.”
|Figure 2. The 260kW inverter installed at O’Brien’s Market in Modesto, California.|
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Casey Miller received his BS in mechanical engineering from Oregon State U. and a master’s in engineering from Stanford U. He is a Director of Product Management at Advanced Energy, Renewables, 20720 Brinson Blvd, Bend, OR 97708.; ph.: 541-323-4155; email@example.com